Anatomical position and directional terms

The anatomical position

Anatomical position is defined precisely so that it never depends on what the person is actually doing. The body stands erect, the head and eyes face forward, the upper limbs hang at the sides, the palms face forward with the thumbs pointing away from the body, and the lower limbs are straight with the feet flat and the toes forward. Two features are easy to forget and matter most: the palms face forward, and the feet point forward. With the palms forward, the radius and ulna lie side by side: the radius is on the thumb side (lateral) and the ulna on the little-finger side (medial). Anatomical descriptions retain this reference even when the forearm rotates. A person lying face up is described as supine; face down is prone. Neither changes the anatomical position, which is only a reference frame for describing the body.

For example: The thumb is described as lateral to the little finger in the standard reference position. Turning your hand does not rename its anatomical sides: the palm remains the anterior surface of the hand.

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Head, feet, front and back

Start with two pairs. Superior means towards the head; inferior means towards the feet. Anterior means towards the front of the body; posterior means towards the back. For the trunk, ventral and dorsal are alternative terms for anterior and posterior. These directions follow the body’s reference position, not gravity or the observer. A person lying on their back still has a chest anterior to their spine.

For example: The nose is superior to the mouth. The breastbone is anterior to the spine; the spine is posterior to the breastbone.

Towards and away from the midline

Imagine a line down the centre of the body dividing right from left. Medial means nearer this midline; lateral means farther from it. These words compare structures rather than naming the patient’s right or left. Both shoulders are lateral to the breastbone. Intermediate describes a structure between a more medial and a more lateral structure.

For example: The little finger is medial to the thumb in anatomical position. The middle finger is intermediate between them. Find these relationships on your own hand with the palm facing forward.

Along a limb and beneath the surface

Proximal means nearer a limb’s attachment to the trunk; distal means farther along the limb from that attachment. The elbow is distal to the shoulder but proximal to the wrist. A second pair describes depth: superficial means closer to the body surface and deep means farther from it. Skin is superficial to muscle; muscle is deep to skin. Depth does not mean above or below on the page.

For example: Raising your hand above your head does not make the wrist proximal to the elbow. Its position along the limb is unchanged.

Common misconception: Always give the reference: a structure can be deep to skin but superficial to another structure.

Left and right belong to the patient

In health care, right and left always refer to the patient, never to the person looking. When you face a patient, their right side is on your left. Writing “right arm” without this convention would be dangerous, so the rule is absolute: the patient’s right is the side on which their own right hand lies. The same principle applies to paired structures: the right kidney, the left lung and the right atrium are named from the patient’s point of view. If you are describing an image, say clearly whether it is an anterior or posterior view and whose right side is shown. Precision here prevents the most basic and most serious kind of error in clinical communication.

For example: A patient reports pain in the right lower abdomen. The nurse examines the patient’s own right side, which appears on the nurse’s left when facing them.

Combining terms to describe a precise location

A precise description usually combines several terms and a landmark. Instead of “a cut on the arm”, say “a cut on the anterior surface of the right forearm, midway between the elbow and the wrist”. Each phrase adds information: anterior gives the surface, right gives the side, forearm gives the region, and the midpoint gives the position along the limb. Proximal or distal needs a reference landmark and does not by itself mean “midway”. Clinicians also use planes and regions, which you will meet in later sections, but the directional pairs already allow accurate statements. When you describe a finding, name the side first, then the region, then the surface or depth, and finally the position along the structure. This order becomes a habit that makes your notes unambiguous.

For example: “A 3 cm wound on the posterior aspect of the left leg, just distal to the knee” locates the injury without a picture.

Terms that describe posture and side

Some terms describe the whole body rather than one part. Supine means lying face up, prone means lying face down, and lateral recumbent means lying on one side. Unilateral means affecting one side only, bilateral means both sides, ipsilateral means on the same side as a reference point, and contralateral means on the opposite side. These words are common in notes and handovers, and they save long explanations. For example, “weakness of the right arm with ipsilateral facial droop” places both findings on the same side, which is an important clue during a suspected stroke. As with directional terms, the meaning is fixed and does not depend on the observer’s position, which is exactly why professional communication relies on them.

For example: A patient who cannot move the left arm and has left-sided facial weakness has unilateral left-sided findings; the two signs are ipsilateral to each other.